Pnuematic Conveying Machine

Pneumatic Conveying System

INTRODUCTION With continuous improvement in technology over the past 20 years, pneumatic conveying now competes favorably with conventional bulk material conveying systems both in terms of operational cost and conveying reliability. In addition to improvement in basic system design, a variety of reliable control components and equipments are available that enable both vendors and users to exploit the flexibility and relative ease of operation of such systems. Basically the system can be used for application like conveying plastic granules in plastic industries, an a vacuum cleaner, in sugar industries, on shipyards, in agricultural departments and much more which in discussed further. Various systems are available for conveying materials but we have decided pneumatic system as it gives solution for automation at low cost. Also the advantages of pneumatic system are discussed later on.

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Pneumatic Conveying System

SELECTION OF SYSTEM We have selected here the pneumatic conveying system for conveying plastic granules as well as dust free operation 1. Operating under vacuum provides the advantage of dust free conditions around the inlet and because any accidental leakage is inward, provides maximum safety in handling toxic products. 2. Ease of automation and control. 3. One pipeline can be used for variety of products. 4. High operation reliability due to few moving machine parts. 5. Flexibility in routing. 6. Careful and gentle handling of produces. 7. Low maintenance and low manpower cost. 8. Minimum floor space.

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Pneumatic Conveying System

THEORY (A) TYPES OF CONVEYING SYSTEM : There are basically three types of conveying systems which are used for conveying material in the industries. (i)

Mechanical conveying System

(ii)

Pneumatic conveying system

(iii)

Hydraulic conveying System

ADVANTAGE OF PNEUMATIC CONVEYING SYSTEM OVER MECHANICAL Pneumatic conveying System Mechanical conveying System 1) Used to convey bulk material in the 1) Used to convey material which is form

of

granules. 2) This

powder, can

short process

fibres

and solid and lumpy.

material 2) Only convey material.

simultaneously with conveying. 3) These systems have air and gas 3) These systems have dust problems. tightened so eliminates dust hazards and dust nuisances. 4) Less reduction of losses. 4) More losses as compared. 5) Less floor space. 5) More floor space. 6) These system required high power (10 6) Less them pneumatic conveyor to 15 times more than mechanical conveyor) 7) Rapid wear of equipment.

7) Less wear of equipment. 3

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Pneumatic Conveying System 8) Noisy

8)

Less

noisy

as

pneumatic. 9) Horizontally as well as vertically 9) Only horizontally (inclined) material can be conveyed.

compared and

to

slightly

inclined (10 to 15 degree) material can be conveyed.

(B) TYPES OF DUST COLLECTOR : Depending upon the type of plant, the type of dust, size of dust, working conditions, efficiency required, cost of device, availability of space, water and power requirements etc., various types of dust collectors are available. These devices take the advantage of certain physical or electrical properties of particular matter of the dust stream. Dust collecting devices can be classified as below :

Dust collection Devices

Mechanical

Electrical Electrostatic Precipitator (ESP) 4

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Pneumatic Conveying System

Dry type

Wet type

Gravitational sep. (Scrubber) Inertial Sep. (Knock-out or Baffle type)

Packed type

Spray Tower

Centrifugal Collector (Cyclone dust collectors )

Venturi Scrubber

Fabrics Filters

Cyclone Scrubber

But whatever type of collecting device be employed, following requirements must be satisfied 1) It should be leak-proof. 2) It should withstand the abrasive and corrosive properties of dust. 3) It should be inert with the gas containing dust. 4) It should withstand the working condition like temperature working velocity etc.

(C) PNEUMATIC CONVEYING SYSTEM Pneumatic conveying is a method of transporting bulk materials in the form of powder, short fibre and granules over a pipeline as a mixture with air or due

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Pneumatic Conveying System to pressure of air such an installation will convey over more than 2 km at a rate of upto 400 tones per hour. It is also capable of lifting loads to a height of 100 meters. Types of pneumatic conveying system as follows : Pneumatic conveying system

Suspension flow

Non-suspension flow

( Dilute phase )

(Dense phase)

Pressure

Single plug

Vacuum

Multiple plugs (Timed pulse)

Combination Pressure vacuum

External air bypass Internal air bypass

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Pneumatic Conveying System

a) SUCCTION TYPE CONVEYOR b) PRESSURE TYPE CONVEYOR

Engineers planning to install a pneumatic conveying system will head to decide whether to use 'dilute' of 'dense' phase system or commercial variations of these basic types. A dilute phase conveying will mean suspension flow where the conveying pipe at relatively low pressure and high velocities. The material to be conveyed is introduced into pipeline in a controlled manner allowing the particles to be carried in suspension to the destination point. The material loading factor, the

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Pneumatic Conveying System weight ratio of material to air is generally in the range of 10- 15 at the higher ends (i.e. 10 kg to 15 kg of material per kg of air). In dense phase conveying, however the material is moved in the conveying pipe to the destination in non suspension flow in collapsing/ reforming dunes or in plugs of full pipe cross section. The pressure required are higher than those required for dilute phase conveying and the material loading considerably grater even going upto 200 depending on the ability of material to be conveyed in this mode. Dense phase conveying is essentially a batch operation as compared to dilute phase conveying which is a continuous operation.

The higher pressure

involved in dense phase conveying and higher material loading require

robust

equipment and specification of valve, actuator etc. should consider the cyclic nature of operation. Vacuum system This consists of piping and pick up manifold which can be y - branch where the material drops into the air system and is pulled vacuum thereby eliminating dust at pickup source.

Negative Pressure Conveying System C.O.E. & T.,Akola

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Pneumatic Conveying System This type of system can be used in these operations where product must be fed into a dump hopper. The conveying air can be used to control the dust that is generated from the dumping operation. An air intake scoop or filler is required depending on the products to be handled. The receiver can be a cyclone connected with a centrifugal fan that will tolerate small amount of product and dust passing through it. However, if a rotary positive displacement blower is the vacuum source, the receiver must be a filler type to prevent any product passing through the blower because of its close tolerances. These systems are particularly suited to moving material from multiple pickup points to a single location, the reason being that the bulk of systems expense is in the terminal end where the receiver, rotary valve and vacuum source are located. These systems are particularly suitable for unloading railroad cars from above the rail. They are also used for picking up from boxcars or flat storage. The advantage of vacuum system is that it provides air to

purge grinding

equipment, pulls the product into the grinder and dissipates the heat of grinding. These system

are excellent for handling toxic materials or corrosive materials

because all leakage is inword so there is less danger of any product escaping into the atmosphere. Vacuum systems have been used extensively for flash drying and cooling.

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Pneumatic Conveying System

Fig. (A) Simple vacuum system These systems can be arranged in closed loop to assure that no product gets out into atmosphere or that b minimum product gets into the atmosphere should a bag break fig. B.

Fig. (B) Closed Loop Vacuum System with Fan 10

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Pneumatic Conveying System It helps to economize on the size of filler in this particular arrangement because the filler is only handling about 10% of the conveying air. The primary cyclone collector as a carryover of 1% or less, passing enough the fan and being blown into the filler. The other 90 % of air continuous on down the outlet of the so that dust in the air eventually gets separated. Fig. C shows a closed loop vacuum system utilizing a rotary positive displacement blower. But in this case the filter must handle 100% of the air because the blower can not tolerate any product passing through it. The zero point is on the discharge of that blower (As the system is entirely vacuum) as indicated in the fig. by the negative signs all the way to the inlet of the blower.

Fig. (C) Closed loop vacuum system with rotary positive displacement blower. 11

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Pneumatic Conveying System The only pressure in the system is from the blower discharge to the zero point, which need be nothing more than a tee open to the atmosphere. Since this is the vacuum system, air will leak in through the rotary valves at the pick and terminal points of the system. This filtered leakage air is exhausted at the zero point. The dust that is collected by the filter is set up to drop right back into conveying line, eliminating the need for rehandling the dust. Application of Pneumatic conveying system : There are huge application of pneumatic conveying system. Some are given below 1) It is used in plastic industries for conveying plastic granules. 2) It is used for collecting dust (as a vacuum cleaner) in officer, bank, departmental stores, houses, colleges. 3) It is used in steel industries. 4) It is used in sugar industries. 5) It is used in shipyards. 6) It is used in agriculture department. 7) It is used as a chip collector in machines. 8) It is used in chemical industries to remove harmful gases. 9) It is used in marble industries. 10) It is used in cosmetics industries. 11) It is used in power plant as well as in coal industries. 12) It is used in cotton industries. 12

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Pneumatic Conveying System 13) It is used in post office and much more.

Key system components : The key components of the system are as follows:  Source of negative pressure air Fan/Vacuum pump.  Receiving equipments like bagfilter, cyclone.  Conveying piping, bends.  Rotary airlock border.  Pick up devices like nozzles or a pipe.  Electric drive.

Fig. Pneumatic (Vacuum) System for conveying plastic granules/ dust collector 13

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Pneumatic Conveying System (1) BLOWER : A blower according to the compressed Air institute is a machine to compress air or gas by centrifugal force to a final pressure not existing 35 lb per sq. in. ga. It is not water cooled as the added expense of the cooling system is not justified in view of the relatively slight gain at these pressure. When used for special application the blowers are some times given other names. In gas service a blower used to remove gas from a coke oven is known as an exhauster. If the pressure at the suction is about atmospheric (as some times used in chemical industry where sufficient head must be developed to circulate the gases through the pressure) the blower is known as booster or circulator. The terms blower, compressor and fan are frequently used interchangeably.

In general a fan operates at low pressure upto 1 psi whereas

blower operates at a pressure upto 35 psi. Types of Blower:Types of blower are as follows :a) Roots blower i)

Two lobe type

ii)

Three lobe type

iii)

Four lobe type

b) Vane type blower c) Centrifugal blower i)

Airfoil type blower (92% efficiency) 14

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Pneumatic Conveying System ii)

Backward-curved type blower (85% efficiency)

iii)

Backward - inclined type blower (78% efficiency)

iv)

Radial - tip type blower (70 % efficiency)

v)

Forward-curved type blower (65% efficiency)

vi)

Radial-blade type blower (60% efficiency)

d) Cross-flow blower e) Vortex blower f) Cupola blower. g) Sewage accretion blower h) Blast furnace gas blower i) Air-actuated (fluidized) conveying type blower. (2) FAN :In selecting fans, the manufacturer's charts should be consulted. The fan tends to run wild, making motor selection difficult. The fan consists of a rotating member, called the wheel or impeller, and a stationary member called the housing. The housing is provided with an intake opening (inlet) and with a discharge opening (outlet). The flow of air or gas is caused by the pressure differential created by the energy transmitted to the gas by the rotating wheel. If no resistance to flow exists, as in the case of a fan in free space with no inlet and no outlet duct, the fan provides the gas with velocity energy only, and no compression or refraction occurs. When either inlet or outlet duct is added frictional resistance is imposed and partial compression occurs on the outlet 15

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Pneumatic Conveying System side, whereas partial refraction occurs on the inlet side. The extent of the resistance imposed at the discharge governs the quantity of gas delivered by the fan. The greatest volume is delivered under zero resistance or "free delivery" conditions. As the resistance to flow is increased, the volume is decreased progressively until at infinite resistance the volumetric delivery is zero, corresponding to "blocked tight" or "static no delivery" condition. In case of blowers the fans are used to force air under pressure, that is, the resistance to gas flow is imposed primarily upon the discharge. Laws of fans :1) The volume of air delivered by a fan is directly proportional to its speed and rotation. 2) The pressure developed by a fan is directly proportional to square of fan speed. These laws are mainly of interest to for operations of engines driving fan, speed of rotation which can be instantly changed. They are of importance when engines and motors are being matched to fan with regard to the power will be absorbed as the result of altering fan speed. Types of fans :Various types of fans are as follows a)

Propeller Fan :- A propeller fan consists of a propeller or disk type wheel within a mounting ring or plate and including driving mechanism supports either for belt drive or direct connection.

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Pneumatic Conveying System b)

Tube axial Fan :- A tube axial fan consists of a propeller or disk type wheel within a cylinder and including driving mechanism supports either for belt drive or direct connection.

c)

Vane axial Fan :- A vane axial fan consists of a disk type wheel within a cylinder, a set of air guide vanes located either before or after the wheel and including driving mechanism supports either for belt drive or direct connection.

d)

Centrifugal Fan:- A centrifugal fan consists of a fan rotor or wheel within a scroll type of housing and including driving mechanism supports either for belt drive or direct connection.

Fan Outlet : The outlet of the centrifugal fan is the termination of scroll shape housing i.e. the point of connection of fan to external system. The arrangement of the outlet connection can contribute to the elimination of losses, making more of the total input available to the system. Avoidance of abrupt or excessive expansion, restrictive sections, abrupt turns or rapid change in directions is good practice. Fig. shows more common precautions to be exercise in disposition of fan outlet connections.

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Pneumatic Conveying System

(A) Ideal conditions – straight outlet duct Excessive expansion High turbulence losses

Normal expansion Minimum turbulence losses (B) Poor

(C) Good Controlled expansion Minimum velocity head loss

Abrupt expansion Complete velocity head loss (D) Poor

(E) Good

Restrictive turn High pressure losses 2 to 4 velocity heads (F) Poor

(G) Good

Efficient turn Low pressure losses ½ to 1 velocity heads Efficient turn Low losses ½ to 1 velocity heads

Restrictive turn High losses 1 to 3 velocity heads (H) Poor

(I) Good Noninterference and minimum losses

Interference and high losses

(J) Poor

(K) Good Fig. Outlet Connections

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Schematic sketch of a typical centrifugal fan wheel with ten backward-curved airfoil blades having the maximum permissible width b. Note : d1, blade o.d.; b, blade width; l, blade length; β1, blade angle at leading edge; β2 blade angle at blade tip; V B1, blade velocity (fpm) at leading edge of blade; V B2, blade velocity (fpm) at blade tip; W 1, relative air velocity (fpm) at leading edge of blade; W2, relative air velocity air velocity (fpm) at blade tip; V 1, resulting absolute air velocity (fpm) at leading edge of blade; resulting absolute air velocity (fpm) at blade tip.

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Pneumatic Conveying System Six blade shapes commonly used in centrifugal fans. The approximate maximum efficiency attainable for each type is shown. (3) BAG FILTER :Filtration is one of the most reliable, efficient and economic methods by which particulate matter

can be removed from gases.

Bag filter provide a

physical barrier ( the filter cloth ) for the separation of material and air and are essential where fine particles are being conveyed.

Bag filters can efficiently

separate fine dusts. The bags need to be cleaned continuously to provide continued efficiency of separation. Reverse pulse jets of compressed air perform this function and are timed to release into the bags in bursts of 100 to 300 milliseconds at frequencies between 1 and 30 seconds. They can be cleaned by rapping, shaking or vibration. The filter is in the form of a fabric bag arrangement tubular bags or as cloth envelops, and is suitable for a dust loading of the order of 1 gm/m 3. A bag house or bag filter consists of numerous vertical bags 120-400 mm diameter and 210 m long. They are suspended with open ends attached to a manifold. The hopper at the bottoms serves as a collector for the dust. The gas entering through the inlet pipe strikes a baffle plate, which causes the larger particles to fall into a hopper due to gravity. The carrier gas then flows upwards into the tubes and then outward through the fabric leaving the particulate matter as a 'cake' on the inside of the bags. Fabric filters are gaining

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Pneumatic Conveying System importance in cement industry as problems like binding tendency, insufficient cleaning, maintenance difficulty etc. are solved satisfactorily by those. (4) CYCLONE COLLECTOR ( CHAMBER ) :It consists of a vertically placed cylinder which has an inverted conic attached to its base. The particulate laden gas stream enters tangentially at the inlet point into the cylindrical opening at the top. The dust particulate are collected at the bottom in a storage hopper. The gas path generally follows a double vortex. First, the gas spirals downwards at the outer periphery of the cylindrical portion continues through the conical portion and reaches the bottom. The gas stream then moves upwards in a narrower inner spiral, concentric with the first and leaves through the outlet pipe. Due to the rapid spiraling movement of the gas, the deeper solids are projected towards the wall by the centrifugal force and then they drop by gravity to the bottom of the body, where they are collected in the storage. One particular cyclone efficiency problem is the formation of eddies at the top of the unit where the dirty gas is introduced. The turbulence in the eddies causes some of the incoming dirty gas to be mixed with the outgoing clean gas of stream. The effect of this problem can be minimized by adding a central tube called a vertex finder which projects into the cyclone body below the turbulent entry region to confine the rising inner gas spiral.

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Pneumatic Conveying System To get increased efficiency, specially for the collection of smaller sized particles, a small diameter, lone taper cyclone should be used. Centrifugal action increases with decreasing radius of rotation.

(5) ROTARY AIR LOCK VALVES :The one item in a pneumatic system that is hardest to properly size is airlock or rotary valve. These not any vane valves can be airlocks or feeder valves or a combination of the two. One type is gravity feeder. It is usually underneath a container, bin or hopper where it measures out an amount of product into another piece of equipment without any differential pressure across the valve. There is no pressure differential to consider so air flow and leakage are not concerns. To size such valves take the displacement figure of the rotor in cubic feet per revolution and figure out the speed the valve must run to deliver and multiply by cubic feet per hr. Another typical gravity feeder application is the same unit feeding out of a container into a negative system at the pickup pt, such that air leakage will be down through the rotary valve in same direction of flow as the product.

This

indicates that there is no reverse flow of air or blow back to consider. This valve is sized the same as previous one because it, too serves as a metering device with no regard for any problems with reverse air flow. An airlock serving as an air seal only, is used when introducing product from another feeding device into a pressure (positive) pneumatic system. 22

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Pneumatic Conveying System Another application of pure airlock is at the outlet of a vaccum system. This is similar to inlet of a pressure system. There is a pressure differential across the valve and the leakage air is going to move from atmosphere into the vaccum receiving vessel in a reverse direction to the product passing through the valve. The product coming into this vaccum receiver is fed into vaccum system by another means, so that it is an stream with no head of product above the valve. If there is head of material above the valve, it is considered as feeder. If it is sealing a pressure differential at the same time, it is airlock feeder. If it is vast a feeder, it would have a head of material with no pressure differential. If it is just airlock, it would have no head, but does have pressure differential. Following table shows criteria for picking a size and valve for a particular application. 1 st column show size of valve ( if diameter and length ). Next column cubic feet displacement of rotor, third column shows normal speed for valve, next 4th column shows total displacement of rotor in cubic feet per hr, 5 th column shows 50% of total displacement and last one shows displacement of rotor at 25 rpm in cubic feet per hr.

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Pneumatic Conveying System

Selection Table Size

4x3 6x4 8x6 10x8 14x10 16x14 20x18 24x22 30x26

Ft3/rev.

0.0119 0.03 0.118 0.24 0.68 1.2 2.5 4.5 8.3

Normal Total rpm for displacement airlock (ft3/hr) 45 45 45 45 45 45 35 31 30

32 82 314 648 1,836 3,306 5,250 8,370 14,940

50% total Gravity displacement. feeder (ft3/hr.) 100% capacity 25 rpm 16 18 41 45 157 171 324 361 918 1021 1653 1800 2625 3750 4185 6760 7470 12450

at

(6) DUCTING :Also called pipeline.

Pipelines are generally of steel/ERW pipes.

Where the conveyed material is not compatible with steal, stainless steal and aluminium are generally used. Stainless steal pipes can be this walled for economy. In petrochemical industry, Special internal treatment to pipelines is sometimes required to reduce frictional heat and consequent pellet melting when the pellets hit the pipe inside during pneumatic transport.

This leaves a characteristic

streamer/angel to hair which is result of solidification of pellet. Long radius bends have radii generally in the range of 12/15 times pipe dia. The bends must be crinkle free on the insides. In case of choked pipelines 24

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Pneumatic Conveying System use of separate compressed air in lets at critical sections of conveying pipeline, especially at bends, is also resorted to. In long conveying lines, the pipelines should be stopped to higher diameters towards the discharge end to reduce conveying velocities. This is specially required where delicate materials are handed and needs controlled conveying velocities. (7) NOZZLE :There are three types and nozzles 1) Convergent nozzle 2) Divergent nozzle 3) Convergent - divergent nozzle

1) Convergent Nozzle

2) Divergent Nozzle

3) Convergent-Divergent Nozzle

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Pneumatic Conveying System (8) ARRANGEMENT OF DRIVES. Arrangement 1. For belt drive. Wheel overhung. Bearings on pedestal.

Arrangement 5. For direct drive, Wheel overhung. Includes housing, wheel, shaft, one intermediate bearing, flanged coupling and pedestal only for motor or engine.

Arrangement 2. For belt drive. Pulley and wheel overhung. Bearings in bracket on fan housing. Made only in smaller sizes for reversible discharge.

Arrangement 6. For direct drive. Three bearing arrangement with fan bearing at inlet side. Includes housing, wheel, shaft, one bearing (in inlet), rigid coupling, and pedestal only for motor or engine.

Arrangement 3. For belt drive. Pulley overhung. Bearings supported on fan. housing.

Arrangement 7. For direct drive, similar to arrangement 6, but with two bearings on fan, and flexible instead of rigid coupling.

Arrangement 4. For direct drive. Wheel overhung. No bearings on fan. Wheel mounted on motor or engine shaft. Pedestal for motor or engine.

Arrangement 8. Similar to arrangement 5, but with two bearings on pedestal with motor, and flexible instead of rigid coupling.

(D) DESIGN

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Pneumatic Conveying System Design Parameters Before designing or selecting pneumatic system, same factors must be known. Most important is capacity to be conveyed, the distance over which the product will be moved and no. of elbows involved. Elbows create large pressure drop in air system so it is required to minimize elbows. The no. and type of pick up location must be known as well air requirements for then. If any heating, cooling or drying is to be accomplished, these factor too could be major sizing section. In the conveying medium is air or gas. In product explosive, does it requirement gas blankets. Should system be open or closed. Are notary valves permissible. To product non abrasive so rotary valve . Works satisfactorily or will it degraded.

A pneumatic system has to be fed evenly to prevent plugging of

system. Approach towards Design of System Basic Data 1) Material Density 2) Distance of Conveying 3) Quantity to convey ( Volume ) Design 1) Ducting length and diameter. 2) Blower capacity. Pressure Air Volume (CFM)

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Pneumatic Conveying System Accordingly to blower design on basis of data of pressure and Air volume. Chamber Size Design Filter Design :- Filter is designed on basis of dust size. We have taken 5 micron Valve Design :- Valve in Designed on basis of discharge rate rpm. We have selected rotary our lock valve. Design Considerations. As per following considerations we have to design our system. We have,

Total Pressure = Static Pressure + Velocity Pressure. For finding pressure on granules we have Static Pressure = ( weight of granules/Area )icy/Cm 2 For calculating power output of fan in HP Hp = CFM × TP

We have

6356 We have considered hp = 1 Therefore,

2 CFM = ( 6356/TP ) For calculating external and internal

We have Internal dia,

d 1 = 10

3

CFM rpm

= 8.1216 inch = 203.04 mm 18000  External diameter, d 2 =   * SP  rpm  28

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Pneumatic Conveying System = 15.74 inch = 393.5 mm Blade width,

b = (0.46)d1 = (0.46) * 8.1216 = 3.73 inch = 93.25 mm

Number of blades = 10 Casing dimensions Width of casing

w = 2.14 * blade width = 7.98 inch = 199.5

r1 = 71.2 % of d2 = 10.72 inch = 268 mm r2 = 83.7% of d2 = 10.55 inch = 313.75 mm r3 = 96.2 % of d2 = 14.43 inch = 360.75 mm Cut of clearance

C = 5 % of d2 = 0.75 inch = 18.75 mm

Outlet diameter of housing

h = 1.12*d2 – 0.3 (1.12 * d2 ) = 11.76 inch = 2.94 mm

Now, Velocity pressure =

 Velocity of air    4005

 5000  =   4005  = 1.55 inch = 38.75 mm 29

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Pneumatic Conveying System and static pressure = 6 inch = 152.44 mm therefore, Total pressure = 6 + 1.55 = 7.55 inch = 188.75 mm Power

CFM × T .P. 6356

=

=

1500 × 7.55 6356

= 1.76 H.P. Therefore use 2 H.P. motor. Belt Design : We have selected here V-belt (B-54) for transmission of power from motor to blower. Length of belt = π( R 1 + R 2 ) + 2X +

( R 2 − R1 ) 2 X

L = Belt length R1 = Radius of smaller pulley in mm R2 = Radius of larger pulley in mm X = Centre distance of two pulley in mm = 3.14 ( 37.5 + 75) + 2 × 506 + = 1371.6 mm

( 75 − 37.5) 2 506

= 54 inch

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Pneumatic Conveying System

Fig. Impeller Design

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Pneumatic Conveying System

Fig. Chamber Design

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Pneumatic Conveying System The successful and efficient operation of complete pneumatic conveying system will depend primarily an proper system design and correct specifications of components should be properly matched to system requirement specially with relation to product handled. (E) SYSTEM RELIABILITY : A reliable pneumatic conveying system will deliver the required capacity with no associated problems. However it is easier said than done because of large no. of variables involved. The designer should consider each part of system independently of system while designing at same time should be able to match interfaces between units of each section. Some of common system problems are 1. System Choker 2. Excessive dust and blow back 3. Excessive power consumption 4. Low throughput. Component Reliability. Failure of operating component of pneumatic system like slide gates diverter valves etc are largely due to the all - pervasive nature of dust. The features which are valve looked for individual components are effective sealing, low friction of sliding materials and methods to prevent powder from remaining and collecting in the units. Practical Trouble Shooting Tips 33

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Pneumatic Conveying System (1) Confirm Correct Conveying Velocity. (2) Confirm feed rate into system. (3) Confirm Phase Density. (4) Check Adequacy of filter Area

(F) PERFORMANCE AND TESTING OF BLOWER :In performance and testing of blower, we consider the calculation of static pressure as well as velocity pressure. 1) Static pressure calculation :-

Fig. Static pressure Calculation Fig. Shows a cylinder with a piston that can be moved up or down. It also shows a U-tube manometer indicating zero pressure.

This means that the

pressure below the piston is same as the barometric pressure in the surrounding air. As the piston is moved down, the air volume below the piston is compressed manometer will register a positive static pressure relative to the atmospheric 34

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Pneumatic Conveying System pressure, which is considered as zero pressure.

This compressed air then has

potential energy i.e. the potential to expand to its original volume. If on the other hand, the piston is raised, the air volume below the piston is expanded and the manometer will register a negative static pressure relative to the atmospheric pressure. This expanded air has also potential energy i.e the potential to contract to its original volume.

This explains the concept of positive and negative static

pressure in stationary air. Velocity pressure calculation : CFM is find out by means of anemometer. Velocity pressure =

Velocityofair 4005

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MODIFICATION The reader should regret that we have manufactured the system according to our convenience and in the era of some limitation of source of manufacturing. But some good modifications can be done in the system likewise, a) Suction points may be increased as per requirement. b) Also the delivery points may be increased c) System may be used as the separator e.g. for removal of smokes, very find dust particle. d) Rotary air lock valve may be used instead of dead weight e) System may be used for conveying heavy particles by increasing R.P.M. of drive(motor).

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COST ESTIMATION Definition :“Cost estimating may be defined as the process of fore costing the expenses that must be incurred to manufacture a product.” Cost estimates are the job product of the engineer and the cost accountant, and involves two factor: physical data and closing data. The cost complies and applies the costing data. Cost Structure :The elements of cost can be combined to give following type of cost 1) Prime Cost :- Prime cost or direct cost is given as Prime cost = Direct material cost + Direct labour cost + Direct expenses. 2) Factory cost : This cost is given as Factory cost = Prime cost + Factory expenses. It is also called as ‘ Works costs’ 3) Manufacturing cost : It is given as Manufacturing cost = Factory cost + Administrative expenses. 4) Total cost :- It is given as Total cost = Manufacturing cost + Selling and distribution expenses. 5) Selling price :- It is given as Selling price = Total cost + Profit

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Pneumatic Conveying System

COST ESTIMATION OF THE SYSTEM Sr.No. 1 2 3 4 5 6 7 8 9

Parts

Material M.S. M.S. M.S. M.S. M.S. C.I.

Qty. 1 1 1 2 1 1

Cost in Rs. 1600 200 200 3500 500 200

Pulley (Small) dia. 75mm V- belt

C.I. B – 54

1 1

145 225

Ducting Motor 2 HP

leather PVC -

1 1

800 3000 10370

Chamber Chamber Stand Bag fitter Blower Bearing Pulley (Big) dia.150mm

Total

CONCLUSION This concept of conveying plastic granules solved lot of problems arised in the convey of granules in plastic Industries. Our system not only have application in plastic industries but also has wide important in various field because of its following benefits. 38

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Pneumatic Conveying System 1) Completely dust free operation 2) Flexibility in routing 3) Careful and gentle handling of product 4) Low maintenance and low manpower cost 5) Minimum floor space. 6) Ease of automation and control. 7) One pipeline can be used for variety of products. 8) High operational reliability due to few moving machine parts. 9) System is used for lifting the material upto 100 meter and convey the material over more than 2 km at a rate of upto 400 tones per hour.

BIBLIOGRAPHY 1) Material handling handbook - Mr. B. Velan 2) Material handling Handbook 2nd edition, edited by Raymond – A Kulwiec 3) Kent’s mechanical Engg. Handbook 39

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Pneumatic Conveying System - By J. Kenneth Sdisburg 4) Thermal Engg. - By R.K. Rajput 5) Fan handbook. -

By Bleier.

40

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Pneumatic Conveying System

SYNOPSIS The trend of material handling has catched popularity in every nook and corner of the world. If you consider modern industry you will find 95% of activities in industry are being carried out automatically. There are various ways or systems that are used to automatic work within industries. But number of experts who have studied the system in details, they come to a conclusion that the automation in material Handling through pneumatic can be carried out at low cost and hence we call it as low cost automation. Pneumatic conveying can be a viable alternative to conventional conveying systems for bulk solids especially for in-plant applications.

Types of system and

commonly specified, components are described in this article. System and component design is discussed here. Reliability is also discussed so that the end user can specify, evaluate and operate pneumatic conveying systems satisfactorily.

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Pneumatic Conveying System

Why A project? An engineer discovers new ideas and, identifies opportunities in various sectors of national economy. He exports

the

possibility

of

standing

a

venture

in

Agriculture, Trade Industry, Transport, Communication and computer science etc. An engineer project is culmination of numerous activities on the part of enterprises, organizes designer, developer, planner, workers and many others. Project is a selection of hard but harmonious labors on the part of above agencies. An engineer is a key element in any project and it is not possible for every engineer to attain success. An engineer

should

possess

certain

qualification

or

characteristics to achieve success on project or task undertaken. The characteristics that contribute to the success of engineer is of his technical competence good judgment,

leadership,

self

confidence,

attitude,

creativeness, honesty and emotional stability. Today the role of an engineer is entirely different than prior to independence. He is exposed to the world of fast changing and challenging technology. With this

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Pneumatic Conveying System

view in mind our first Prime Minister ‘Pandit Jawaharlal Nehru’ expressed the following thoughts. “It is not possible for developing country like us to borrow the technical knoe how, technicians, engineers and scientist and financial assistance from developing countries should develop all their aspects themselves.” To put the thought of this great man, in execution, engineering project is the first step for an engineer. An engineering project is a balanced cocktail of the practical aspect of humanities and economics. An engineer’s ultimate aim is to do well for the society and himself for the same.

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